[pulseaudio-discuss] why is this giving an error and failing to start?

Christ Schlacta lists at aarcane.org
Wed Dec 22 12:04:42 PST 2010

On 12/22/2010 01:41, Colin Guthrie wrote:
> 'Twas brillig, and Christ Schlacta at 21/12/10 19:29 did gyre and gimble:
>> load-module module-combine sink_name=mpd.002 slaves=mpd.001 channels=2
>> load-module module-remap-sink sink_name=mpd.003.lr master=mpd.002
>> channels=2 master_channel_map=left,right channel_map=left,right
>> load-module module-remap-sink sink_name=mpd.003.rl master=mpd.002
>> channels=2 master_channel_map=right,left channel_map=left_right
>> load-module module-combine sink_name=mpd slaves=mpd.003-rl,mpd.003.lr
>> channels=2
>> update-sink-proplist raw device.description="actual soundcard"
>> update-sink-proplist xbmc device.description="XBMC stereo output"
>> update-sink-proplist mpd device.description="MPD Stereo output"
>> ### ENd config snippet.
>> The problem is that I'm getting some perculiar errors on starting
>> pulseaudio:
>> Dec 21 11:19:06 rebirth pulseaudio[14764]: module-combine.c: No slave
>> sinks specified.
> Hmm, interesting. Any idea which of the two combines this message is
> coming from?
I didn't see which iof the two combine's it was coming from, but I did 
manage to get it working
>> Dec 21 11:19:06 rebirth pulseaudio[14764]: module-remap-sink.c: No
>> remapping configured, proceeding nonetheless!
> There appears to be a typo in your last remap where you have
> "channel_map=left_right" when I presume you mean "channel_map=left,right"
I fixed that and found another typo as well.  fixing both typos fixed 

>> then, despite the fact that it says it's proceeding, it simply proceeds
>> to exit with no further log entries.
> Hmm, interesting. Can you run manually via pulseaudio -vvvv (with the
> appropriate --system argument - you'll have to run as root and it should
> drop privs to the "pulse" user)
the -vvv (oops, missed a v) is what saved me, after running it a half 
dozen times and checking the output, it was fixed!  thank you very much!
>> So you may ask what I'm trying to accomplish.  I'm trying to downmix
>> stereo audio to mono before passing it off to the virtual sink mpd.001.
>> the reason is that I've got a blown speaker, that I've gotten rid of and
>> only one speaker left.  THis christmas music sounds terrible when you
>> can't hear alvin, or you can't hear simon and theodore.
> Oh Noes! :p
Never fear!  between your assistance and my persistence, now we can hear 
all the chipmunks and all the muppets too!  Christmas is saved! Yaaay!!
>> If you can help
>> me fix this existing config, or find a better way to downmix my music to
>> mono (actually mix l and r, not just one or the other) I'd be very
>> happy, and the children's christmas would be immeasurably merrier!
> One potentially easier (but maybe not as nice?) way would be to create a
> null sink with a single channel then use module-loopback sink to connect
> it's monitor to your real sink. It should automatically upmix the mono
> null sink to stereo on your real sink.... not 100% sure this will work
> but it should do.
> HTHs
> Col
I didn't try your method, since mine worked after fixing the mistakes.  
Someone who isn't me (IE: someone who understands monitors and 
loopbacks, instead of someone who read enough to put a bastard monster 
together!) should try it.  one of the two methods should end up in the 
FAQ.  Perhaps whichever has the lower CPU overhead?

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